1. Field of the Invention
This invention relates to particle separation apparatus which separates particles by size or by specific gravity.
More particularly, the invention relates to apparatus which separates particles from a liquid slurry by directing the slurry into a particle separation chamber which circulates slurry particles along helical paths in the chamber.
In a further respect, the invention relates to particle separation apparatus of the type described which continues to circulate slurry particles along helical paths of travel after the flow of liquid slurry into the particle separation chamber is discontinued.
In another respect the invention relates to particle separation apparatus of the type described which can readily and efficiently separate from a liquid slurry a particle size fraction which is comprised entirely either of particles less than 150 mesh in size or of particles greater than 3 mesh in size.
In still a further respect, the invention pertains to particle separation apparatus of the type described which does not require a large difference between the inlet pressure and outlet pressure, and which does not require that liquid slurry be directed into the particle separation chamber under pressure in order for the apparatus to operate efficiently.
2. Description of the Related Art
Hydrocyclones are commonly utilized to separate particles from a liquid slurry. The particles are separated by size or by specific gravity. In a hydrocyclone, a slurry is pumped under pressure through an orifice into a conically shaped housing. The conically shaped housing causes the slurry to travel along an ever decreasing helical path. Heavier (or larger) particles segregate along the conical wall of the housing while lighter (or smaller) particles segregate inwardly from the housing wall. Several disadvantages are associated with conventional hydrocyclones. First, if there is an interruption in the flow of pressurized slurry through the orifice into the hydrocyclone, the internal flow of slurry through the hydrocyclone collapses. Second, hydrocyclones are, practically speaking, limited to performing particle separation on slurries which contain particles no larger than about one quarter of an inch. Third, a particular limitation of hydrocyclones is that hydrocyclones can only achieve relatively rough splits when removing particle size fractions from a slurry. Fourth, hydrocyclones do not permit liquid or gas overflow which is at the center of hydrocyclone to be both forced out under pressure generated in the hydrocyclone and suctioned out of the hydrocyclone under vacuum.
Accordingly, it would be highly desirable to provide an improved particle separation apparatus which maintained its internal energy during the ebb and flow of the liquid slurry stream feeding the apparatus, which could readily process slurries containing large or small particles, which could both pump particles out under internal hydrocyclone pressure and draw particles out of the hydrocyclone under vacuum, and which could accurately achieve a greater number of particle splits than conventional hydrocyclones, such splits being made according to particle size or particle specific gravity.
Therefore, it is a principal object of the invention to provide an improved particle separation apparatus.
A further object of the invention is to provide improved apparatus which separates particle size fractions or particle specific gravity fractions from a liquid slurry by directing the slurry into a particle separation chamber which circulates the slurry along uninterrupted continuous helical paths of travel in the separation chamber.
Another object of the invention is to provide improved particle separation apparatus of the type described which maintains the flow of slurry particles along continuous helical paths of travel in the separation chamber even after the input of slurry into the chamber has been discontinued or interrupted.
Still a further object of the invention is to provide improved particle separation apparatus of type described which enables liquid slurry to be input into the particle separation chamber moving only under the force of gravity at atmospheric pressure.
Yet another object of the invention is to provide improved particle separation apparatus of the type described which efficiently produces particle size fractions comprised either of small or large particles.